Method of making a trunnion and bearing body assembly for a universal joint

ABSTRACT

The trunnion and bearing body assembly includes a circular or octagonal center block formed from bar stock and having four equally spaced bores which extend into but not through the center block. The universal joint also includes four trunnions each made from circular cross section bar stock and having a reduced diameter pin-forming section which is received in one of the bores in the center block. A larger diameter portion of each trunnion is receivable in an opening in the yoke forming part of a universal joint. The method includes the steps of forming the center block and the trunnions from two lengths of standard bar stock.

United States Patent Khambatta et al. Apr. 2, 1974- [5 METHOD OF MAKINGA TRUNNION AND 2,304,666 12 1942 Sturges 29 1495 R BEARING BODY ASSEMBLYFOR A ghurphyan-i 6:517 eppar, r ..6 l7 UNIVERSAL JOINT 3,701,18910/1972 Kodono et al. 29/l48.4 A [75] Inventors: Sarosh M. Khambatta,Chicago;

Brian Melfose, both of Primary ExaminerThomas H. Eager Attorney, Agent,or F irm-Thomas R. Vigil; Silver- [73] Assignee: Enrique H. Orazco,Chicago, Ill. a man& Cass part interest [57] ABSTRACT [22] Flled' Sept'1972 The trunnion and bearing body assembly includes a [21] Appl. No.:286,671 circular or octagonal center block formed from bar stock andhaving four equally spaced bores which ex- 52 us. c1. 29/1484 A, 29/1495R, 29/417, tend but The versal omt also includes four trunnlons eachmade 29/430 29/434 64/17 from circular cross section bar stock andhaving a re- [51 Int. Cl..v B23p 11/00, B23p 17/00, B23p 19/00 duceddiameter pin-forming section whlch 1s received [58] Fleld of Search29/148.4 A, 149.5 R, 430,

In one of the bores m the center block. A larger diam- 29/434, 438, 417,64/17 eter portion of each trunmon 1s receivable 1n an opening\in theyoke forming part of a universal joint. The [56] References Clted methodincludes the steps of forming the center block UNITED STATES PATENTS andthe trunnions from two lengths of standard bar 2,238,335 4/1941MacGregor 64/17 stock, 2,291,436 7/1942 Anderson 29/1495 R 1 Claim, 8Drawing Figures PATENTEDAPR 2 m4 3,800 383 SHEET 1 [IF 2 METHOD OFMAKING A TRUNNION AND BEARING BODY ASSEMBLY FOR A UNIVERSAL JOINTBACKGROUND AND SUMMARY OF THE INVENTION The present invention relates toa method of making an improved universal joint. More specifically thepresent invention relates to a trunnion and bearing body assembly foruse in a universal joint.

Most of the presently available universal joints utilize a cross andbearing assembly comprising a center block formed from a forging andhaving four equally spaced trunnions extending therefrom. The trunnionsform a cross and the forged center block is commonly referred to as thecross or spider. Initially the forged center block has four projectionswhich are subsequently machined to form the four trunnions whereby eachtrunnion has a smooth cylindrical surface. The cross and bearingassembly also includes four bearings. The universal joint, of course,includes two yokes with each yoke mounting two bearings. Each bearing isreceived over one of the trunnions. Each of the bearings can consist ofasimple sleeve bearing in a bearing mount or of a needle bearingassembly.

From the foregoing it will be apparent that the manufacture and assemblyof each cross and bearing assembly require several machining andassembly operations which contribute significantly to the cost of eachuniversal joint utilizing a cross and bearing assembly.

Forgings require stress relieving treatment which contributes to thecost thereof. Also defective forgings are periodically encounteredresulting in losses. These losses are even greater when the defects arediscovered after the machining of the trunnions. In view of the largeuse of universal joints in automobiles and trucks, it is desirable tominimize these losses and to simply the manufacture and assembly ofuniversal joints thereby to reduce their cost.

With the trunnion and bearing body assembly of the present invention, itis estimated that a universal joint can be manufactured and assembledfor approximately two-thirds of the cost of conventional universaljoints using a conventional cross and bearing assembly. This cost savingof 30-35 percent is obtained by manufacturing a center block and fourtrunnions from standard bar stock which have consistent metalurgicaluniformity. In the trunnion and bearing body assembly of the invention,four bores are formed in an end portion of bar stock having a circularor octagonal cross section. The end portion having the bores therein isthen separated from the remainder of the bar stock thereby to form thecenter block. The trunnions are likewise formed from a length of barstock which has a circular cross section and which has a smallercross-sectional extent than the bar stock from which the center block isformed. In forming the trunnions, a section of an end portion of the barstock is cut down to form a reduced diameter section and then the endportion is separated from the remainder of the bar stock. The reduceddiameter section forms a trunnion pin which is received in one of thebores of the center block. The larger diameter section of the trunnionis received in an opening in a yoke of the universal joint.

By using a material bar stock which is virtually free of internaldefects by reason of a generally uniform crystalline structure and byemploying programmed machining operations, it is believed that very fewlosses will be incurred in the manufacture of the trunnion and bearingbody assemblies of the invention, the only apparent losses resultingfrom the short pieces of bar stock remaining at the end of a length ofbar stock, which has been cut into a plurality of trunnions or bearingbodies, and these short pieces of bar stock can be salvaged for theirmetal content.

Heretofore, it has been proposed to form a universal joint with a crossblock having bores therein which receive pivot pins mounted to a yoke.An example of such a universal joint which apparently utilizes a centerblock formed from a casting, is disclosed in U.S. Pat. No. 3,213,644.Also, the use of a cylindrical wheel casting assembly made from aplurality of parts for a center body has been proposed in U.S. Pat. No.2,024,777. It has also been proposed in U.S. Pat. Nos. 2,355,781 and3,103,798 to make an intermediate or body portion from square orrectangular bar stock or from tubular stock.

The method and assembly of the present invention differ from thepreviously proposed universal joints in that, according to theinvention, there is provided a method for making a trunnion and bearingbody assembly for a universal joint including the steps of: arranging alength of first bar stock having either a circular or octagonal crosssection in position for intermittent feeding to a first operatingstation; forming at the first operating station four equally spacedcylindrical bores in the bar stock, the axis of each bore beingsubstantially in line with the axis of an opposite bore and beingsubstantially from the axis of the other two bores, the bores openingonto the side surface of the bar stock and extending into but notthrough the bar stock; separating a given length of the end portion withthe bores therein from the remainder of the bar stock thereby to form acenter block for a trunnion and bearing body assembly of a universaljoint; arranging a length of second bar stock having a circular crosssection in position for intermittent feeding to a second operatingstation, the second bar stock having a smaller cross-sectional extentthan the first bar stock; feeding an end portion of the second bar stockto the second operating station; forming a cylindrical section ofreduced diameter in said end portion; separating the end portion withthe cylindrical section from the remainder of the second bar stock toform a trunnion having a pin defined by the reduced diameter section;and forming three additional trunnions in the same manner.

Also, according to the invention, there is provided a trunnion andbearing body assembly for a universal joint, the assembly including acenter block made from bar stock having a circular or octagonal crosssection, and four trunnions made from bar stock having a circular crosssection.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an endportion of octagonal bar stock as it is being formed into a center blockfor a trunnion and bearing body assembly of a universal joint;

FIG. 2 is a perspective view similar to FIG. 1 and showing the centerblock as separated from the remainder of the bar stock;

FIG. 3 is a perspective view of the end portion of a length of circularbar stock just prior to the forming of a trunnion therefrom;

FIG. 4 is a perspective view similar to FIG. 3 showing the end portionof the circular bar stock after an annular section of material has beenremoved to form a reduced diameter pin-forming section;

FIG. 5 is a perspective view similar to FIG. 3 and showing the relativedisplacement movement between the end portion of the bar stock and acutting tool;

FIG. 6 is a perspective view similar to FIG. 3 and showing theseparation of the trunnion formed in the end portion of the bar stockfrom the remainder of the bar stock;

FIG. 7 is a plan view of one embodiment of the trunnion and bearing bodyassembly with portions broken away to show needle bearings surroundingone trunnion pin; and

FIG. 8 is an exploded perspective view of a universal joint utilizingthe trunnion and bearing body assembly of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrateseveral steps of the method of the invention for forming a bearing bodyor center block 10 (FIG. 2) of a trunnion and bearing body assembly 11(FIG. 7) from a length of bar stock 12 having an octagonal crosssection. FIGS. 3-6 illustrate several steps in the method of theinvention for forming one of four trunnions 14 (FIG. 6) for the assembly11 from a length of bar stock 16 having a circular cross section. Thetrunnion and bearing body assembly 11 with the trunnions 14 in thecenter block 10 is shown in FIG. 7 and an exploded view of a universaljoint assembly 18 including the trunnion and bearing body assembly 11and two yokes 20 and 22 is shown in FIG. 8.

Although only octagonal cross-sectional bar stock 12 is shown in FIGS. 1and 2, it is to be understood that, according to the teachings of theinvention, the center block 10 also can be made from bar stock having acircular cross section. Only octagonal or circular bar stock is used inorder to provide a strong and balanced center block 10. In this respectboth strength and balance are enhanced by providing generally annularsegments of material in the block between adjacent bores and by avoidingor minimizing projections on the periphery of the center block. Thesetwo structural features are obtained with circular or octagonal barstock. It is to be noted that a circular block with four equally spacedflats thereon for facilitating drilling of bores therein is essentiallyoctagonal. Although, in octagonal bar stock not all of the volume in theannular segments between bores is filled with material, octagonal stockis preferred since four equally spaced flats are present thereon,thereby facilitating the holding of the bar stock in place and thedrilling of holes therein.

According to the method of the invention, a length of the bar stock 12is arranged in position for feeding an end portion 24 of the bar stock12 to an operating station 26. Typically, this is done with aconventional automatic feed lathe which is operable to intermittentlyfeed the bar stock to the operating station. It is to be understood thatprogramming devices of known type are utilized for controlling theintermittent moving of the bar stock 12 to the operating station 26. Asshown in FIGS. 1 and 2, the bar stock 12 is supported in a collet 28through which it is intermittently slid toward the operating station 26.The amount of travel of the bar stock 12 each time it is fed to theoperating station 26 is equal to the length or thickness of the centerblock 10 to be formed.

At the operating station 26, four equally spaced bores 30 (FIG. 2) areformed in the end portion 24 and a length of the end portion 24 havingthe bores 30 therein is separated from the remainder of the bar stock toform the center block 10 as shown in FIG. 2. In FIGS. 1 and 2, there areshown four gripping members 32 which are movable radially to and fromthe end portion 24 of the bar stock 12 for holding the end portion 24 inplace while the four bores 30 are formed in the end portion 24. Also, inFIGS. 1 and 2, four drills 34 are shown for drilling the four bores 30in the end portion 24. Although not shown in detail, it is to beunderstood that the drills 34 and the support members 32 are part of anoperating mechanism of the lathe and suitable mechanisms (not shown) areprovided for moving the drills 34 and support members 32 inwardly andoutwardly from the bar stock 12 and for operating the drills 34 fordrilling the bores 30 in the end portion 24.

Also, and as will be apparent from FIG. 7, the drills 34 preferably havea special configuration, other than the conventional tip configurationshown in FIG. 2, for forming a flat-bottomed bore with a counterbore.This special type of drill tip is of a known type and the bore formedthereby is shown at 30a in FIG. 7.

The lathe or machine tool for forming the center blocks 10 also includesa device 36 such as a saw blade for cutting through the bar stock 12thereby to separate the end portion 24 from the remainder of the barstock 12 for completing the formation of the center block 10. It is tobe understood, of course, that the cutting device 36 can take otherforms than the saw blade. In this respect, the cutting device could be alaser beam, a cutting torch or a lathe cutting tool.

After the center block 10 is formed as shown in FIG. 2, the method caninclude the further steps of heat treating, finish grinding, buffing,deburring, polishing and/or plating the center block 10.

Also, the method for forming the trunnion and bearing body assembly 11can include the steps of mounting needle bearings 37 in the bore 30a andinserting a retainer ring 38 over the bearings 37 as shown in FIG. 7. Inmost applications, needle bearings 37 are utilized.

As shown in FIGS. 3-6, the method of the invention includes steps formaking a plurality of the trunnions 14 including: arranging the lengthof bar stock 16 for feeding an end portion 39 thereof to a secondoperating station 40 at which there is located a device 42 for removinga portion of the end portion 39 to produce a reduced diameter section 44(FIG. 4) in the end portion 39. In the illustrated embodiment, thedevice 42 is a cutting tool for a machine tool and is arranged forcutting down the end portion 39 totform the reduced diameter section 44which defines a trunnion pin. The machine tool is of known type andincludes a collet 46 through which the length of bar stock 16 is fed.Although not shown, it is to be understood that the machine toolincludes a conventional releasable chuck for holding the bar stock 16while it is rotated and while the cutting tool 42 is fed radially intothe end portion 39. Also, the machine tool includes a suitableconventional mechanism for intermittently feeding the end portion of thebar stock 16 to the second operating station 40.

After the desired cylindrical section 44 has been formed in the endportion 39, the bar stock 16 and/or the cutting device 42 are movedrelative to each other to position the cutting tool 42 for cuttingradially into the bar stock 16 to separate the end portion 39 from theremainder of the bar stock 16 and thereby form the trunnion 14, havingthe reduced diameter pin forming section 44 and a larger diametersection 48. These steps are illustrated in FIGS. 5 and 6. It will beunderstood that in making the trunnion and bearing body assembly 11, thesteps just described are repeated four times to make four trunnions 14.

A preferred trunnion and bearing body assembly 11 is shown in FIG. 7. Inthe assemblyll, a plurality of needle bearings 37 are mounted withineach of the bores 30 as shown for the bore 30a and are held within eachbore by the retainer ring 38 received in the counterbored portion ofeach bore 30. The needle bearings 37, of course, provide smooth rollingfriction between the trunnions 14 and the bores 30 in the center block10.

As shown in FIG. 8, the larger diameter section 48 of each of thetrunnions 14 is received in one of two openings 54 in each of the yokes20 and 22. The mounting of each of the trunnions 14 in one of the bores54 can vary depending upon the construction of the yokes. In thisrespect, the trunnions can be mounted in a variety of conventionalyokes. For example, the trunnions can be received in the bores 54 afterwhich a cover plate is secured over the opening 54 thereby to retain thetrunnions 14.

For mounting in another conventional yoke, a groove can be formed in thelarger diameter section 48 adjacent the shoulder between the section 48and the reduced diameter section 44. A snap ring is positioned betweenone arm of the yoke 20 or 22 and the center block and the trunnion 14 isinserted through the opening 54 with the pin 44 received in one of thebores 30 in the center block 10. Then the snap ring is snapped into thegroove to prevent the trunnion 14 from moving radially outwardly of thecenter block 10.

In still another conventional yoke, an annular groove is formed withinthe opening 54 adjacent the outer end thereof. The length of thetrunnion 14 is then made so that the larger diameter section does notextend past the annular groove in the bore 54 when the pin 44 isreceived into one of the bores 30. In this arrangement, the trunnion 14is inserted through the opening 54 and into one of the bores 30 in thecenter block 10, after which a snap ring is inserted into the opening 54and snapped into the annular groove. The snap ring is then in positionto engage the trunnion 14 and prevent outward movement thereof from thebore 30.

It will be apparent from the foregoing description that the trunnion andbearing body assembly 11 of universal joint 18 is very flexible and canbe utilized with any number of conventional yokes. Thus, the assembly 11shown in FIG. 7 can be utilized as original equipment in the universaljoint 18 or can be used as a replacement assembly for a universal joint.

Further, it will be apparent from the foregoing description that theassembly 11 and the method for making same provide a number ofadvantages, several of which have been described above and others ofwhich are inherent in the invention. Some of these advantages are asfollows:

1. The cost of manufacturing the trunnions 14 and the center block 10 ofthe assembly 11 is estimated to be substantially less than the cost formaking cross and bearing assemblies presently used in conventionaluniversal joints. This savings has been estimated to be 30 to 35 percentand is based on the fact that no forgings are required for the centerblock 10 which is made from standard bar stock and by the fact that noscrew machine blanks or extruded blanks are required for end capportions or bearings since the trunnions 14 are also made from standardbar stock;

2. Assembling of the parts 14 and 10 should take less time than theassembling of conventional equivalent parts. As a result, furthersavings may be incurred in assembling the assembly 11, either onoriginal universal joints or in replacing a conventional cross andbearing assembly in a conventional universal joint;

. Still another advantage is the fact that the method of the inventioncan be easily put into practice without the need for significant toolingcosts inasmuch as standard mass production machine tools can be utilizedfor manufacturing the trunnions 14 and the center blocks 10 with minimalalteration to the machine tools utilized.

4. A universal joint rebuilt with the assembly 11 with the symetrical,circular or octagonal center block 10 does not affect the balance on abalanced shaft assembly after replacement installation;

5. Vibration incurred with the assembly 11 should be less than thatincurred with conventional cross and bearing assemblies since the areaof contact between the pins 44 and bores 30 is closer to the center ofthe universal joint than is the area of contact I between the stubshafts and bearings in a conventional assembly. As a result, a universaljoint 18 utilizing the assembly 11 should provide better reliability anda longer and more efficient working life than universal joints utilizingconventional cross and bearing assemblies;

6. Still another important advantage is the fact that presentlyavailable standard auxiliary parts such as snap rings, bolts, etc., andfriction lubrication parts such as needle roller bearings, seals, etc.,as used in present universal joints, also can be used with the assembly11.

From the foregoing description, it will be apparent to those skilled inthe art that modifications and variations can be made to the method ofthe invention and the trunnion and bearing body assembly formed therebywithout departing from the spirit or scope of the invention.Accordingly, the scope of the invention is only to be limited asnecessitated by the accompanying claims.

We claim:

1. A method for making a trunnion and bearing body assembly for auniversal joint including the steps of: arranging a length of first barstock having either a circular or octagonal cross section in positionfor intermittent feeding to a first operating station; forming at saidfirst operation station four equally spaced cylindrical bores in saidbar stock, the axis of each bore being substantially in line with theaxis of an opposite bore and being substantially 90 from the axis of theother two bores, said bores opening onto the side surface of said barstock and extending into but not through said bar stock; separating agiven length of said end portion with said bores therein from theremainder of said bar stock thereby to form a center block for atrunnion and bearing body assembly of a universal joint; arranging alength of second bar stock having a circular cross seetion in positionfor intermittent feeding to a second opforming three additionaltrunnions in the same manner.

E'UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO.3,800,383 Dated April 2, 19M

Inventor(s) SAROSH M. KHAMBATTA; BRIAN L. ASIMOR It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the Introductory Data, under code (73) change "ORAZCO" to OROZCOSigned and sealed this 17th day of September 1974.

(SEAL) Attest:

MCCOY M. GIBSON vJR. c. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM PO-IOSO (10-69) USCOMM DC eo376 p69 u.s covtmmsm PRINTINGOFFICE: was 0-2ss-:434,

1. A method for making a trunnion and bearing body assembly for auniversal joint including the steps of: arranging a length of first barstock having either a circular or octagonal cross section in positionfor intermittent feeding to a first operating station; forming at saidfirst operation station four equally spaced cylindrical bores in saidbar stock, the axis of each bore being substantially in line with theaxis of an opposite bore and being substantially 90* from the axis ofthe other two bores, said bores opening onto the side surface of saidbar stock and extending into but not through said bar stock; separatinga given length of said end portion with said bores therein from theremainder of said bar stock thereby to form a center block for atrunnion and bearing body assembly of a universal joint; arranging alength of second bar stock having a circular cross section in positionfor intermittent feeding to a second operating station, said second barstock having a smaller crosssectional extent than said first bar stock;feeding an end portion of said second bar stock to said second operatingstation; forming a cylindrical section of reduced diameter in said endportion; separating said end portion with said cylindrical section fromthe remainder of said second bar stock to form a trunnion having a pindefined by said reduced diameter section; and forming three additionaltrunnions in the same manner.